Automatically replaceable apparatus for collecting byproducts and the controlling method thereof in equipment producing semiconductor

ABSTRACT

Disclosed herein are an automatically replaceable apparatus for collecting byproducts in semiconductor producing equipment and a control method thereof. The apparatus includes several trap units mounted to a vertical shaft at regular angular intervals and rotating in response to a driving direction of a servo motor. Upper and lower plates support the vertical shaft, and connect byproduct inlet and outlet ports, cleaning-water supply and discharge ports, and dry-gas supply and exhaust ports to the respective trap units. Trap and plate coupling means are extended at normal times to air-tightly seal gaps between the upper and lower plates and the trap units, and contracted when the trap units are rotated in a predetermined direction for the replacement. The servo motor is mounted to a lower surface of the lower plate and rotates the trap units within a predetermined angular range. A control unit controls the operation of the components.

TECHNICAL FIELD

The present invention relates, in general, to an automaticallyreplaceable apparatus for collecting byproducts in semiconductorproducing equipment and a method of controlling the apparatus and, moreparticularly, to an automatically replaceable apparatus for collectingbyproducts in semiconductor producing equipment and a method ofcontrolling the apparatus, in which several trap units are movably orrotatably installed in the collecting apparatus to collect byproductsproduced during the semiconductor fabricating process, such as poisonousgases (ignitable gas, corrosive gas, noxious gas or harmful compounds),such that, when a predetermined amount of byproduct is collected in anyone of the trap units, the task of collection of the byproduct isautomatically transferred to another trap unit which has been cleaned,thus increasing the operation rate of the byproduct collectingapparatus, therefore increasing the production of semiconductors,preventing injuries to workers due to the effluence of harmfulsubstances or noxious gases which may be produced when the byproductcollecting apparatus is replaced with another one, and ensuring safety.

BACKGROUND ART

Generally, a semiconductor manufacturing process comprises a fabricationprocess and an assembly process. The fabrication process is defined asthe process of manufacturing semiconductor chips in various processchambers. That is, a thin film is deposited on a wafer and selectivelyetched. These steps are repeated, thus processing a specific pattern.Meanwhile, the assembly process is defined as the process ofindividually separating the chips manufactured through the fabricationprocess, and coupling each chip to a lead frame, thus providing afinished product.

In this case, the process of depositing the thin film on the wafer oretching the film deposited on the wafer is conducted in a processchamber at a high temperature using noxious gases, such as Silane,Arsine, or boron chloride, and a process gas, such as hydrogen. Whilethe process is conducted, various kinds of ignitable gases and noxiousgases containing corrosive impurities and noxious elements are producedin the process chamber in large quantities.

Thus, the semiconductor manufacturing equipment is provided with ascrubber. The scrubber is mounted to the rear end of a vacuum pump whichcreates a vacuum in the process chamber, and purifies exhaust gasdischarged from the process chamber prior to being discharged to theatmosphere.

That is, in the fabrication process of depositing the thin film on thewafer, etching the thin film, and repeating the depositing operation andthe etching operation in the process chamber, thus forming a pattern,and thereby manufacturing a semiconductor chip, the byproducts producedin the chamber are fed through an exhaust line to the vacuum pump forcreating a vacuum in the chamber and the scrubber for processing harmfulcompounds.

However, reactive compounds are deposited on the exhaust line, thevacuum pump, the scrubber, and other parts, so that associated apparatusmay develop problems, and the lifespan of the apparatus may beshortened. Consequently, this affects the process of treating the wafer.

In order to solve the problem, as shown in FIG. 1, a collector 3 ismounted between the rear end of the process chamber 1 and the front endof the vacuum pump 2, thus allowing the byproducts fed from the chamberto be immediately collected and received therein.

However, it takes a long time to collect various kinds of reactivebyproducts using one collector 3, and a large amount of byproducts iscollected in the collector 3, so that a gas flow passage is narrowed.Consequently, the pressure of the process chamber required for the wafertreating process cannot be controlled, so that it is difficult toconduct the process.

Thus, when the accumulated amount in the conventional collector, havinga construction limited to a predetermined volume, exceeds apredetermined amount, the collector must be replaced with a new one. Theconventional collector is manually replaced with a new one.

The byproduct collecting apparatus of the semiconductor producingequipment is exposed to and collects ignitable gas, corrosive gas,noxious gas, and harmful compounds. When the byproduct collectingapparatus has been used for a lengthy period of time, the collector isfilled with the byproducts. In order to replace the collector with a newone, the collector itself must be separated from the process chamber. Assuch, when the collector is separated from the chamber, some of theharmful substances or gases are exposed to the outside. This compromisessafety. Further, because of the time spent on the replacement, theoperation rate of the process chamber and the productivity thereof arereduced.

DISCLOSURE OF INVENTION Technical Problem

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide an automatically replaceable apparatus forcollecting byproducts in semiconductor producing equipment and a methodof controlling the apparatus, in which several trap units are rotatablyinstalled in the collecting apparatus to collect byproducts producedduring the semiconductor fabricating process, such as ignitable gas,corrosive gas, noxious gas or harmful compounds, such that, when apredetermined amount of byproduct is collected in any one of the trapunits, the task of collection of the byproduct is automaticallytransferred to another trap unit which has been cleaned, thus increasingthe operation rate of the byproduct collecting apparatus, thereforeincreasing the production of semiconductors, preventing injuries toworkers due to the effluence of harmful substances or noxious gaseswhich may be produced when the byproduct collecting apparatus isreplaced with another one, and ensuring safety.

Technical Solution

In order to accomplish the object, the present invention provides anautomatically replaceable collecting apparatus for collecting byproductsproduced in a semiconductor production line, the collecting apparatusbeing constructed so that a trap collecting various kinds of byproductsis installed in a cylindrical casing which is open at a top and bottomthereof and so that a lid having each of a byproduct inlet port and abyproduct outlet port is mounted to each of upper and lower openings ofthe casing to close each of the upper and lower openings, and beinginstalled between a process chamber and a vacuum pump, the collectingapparatus including a plurality of trap units, upper an lower plates,trap and plate coupling means, a servo motor, pressure gauges, upper andlower isolation valves, cleaning-water supply and discharge valves anddry-gas supply and exhaust valves, and a control unit.

The trap units are mounted to a vertical shaft provided in the center ofthe casing at regular angular intervals, and rotate leftwards orrightwards between upper and lower plates in response to a drivingdirection of a motor. While the trap units are connected to byproductinlet and outlet ports, cleaning-water supply and discharge ports, anddry-gas supply and exhaust ports, one of the trap units collects thebyproducts and the rest of the trap units are repeatedly cleaned.

The upper and lower plates support the vertical shaft to which the trapunits are mounted such that the vertical shaft passes through centers ofthe upper and lower plates, and are provided around the trap units to bespaced apart from the upper and lower lids by a predetermined interval,and are provided with the byproduct inlet and outlet ports, thecleaning-water supply and discharge ports, and the dry-gas supply andexhaust ports. The upper and lower plates contact the upper and loweropenings of the trap units at upper and lower positions of the casing,and connect the byproduct inlet and outlet ports, the cleaning-watersupply and discharge ports, and the dry-gas supply and exhaust ports tothe respective trap units.

The trap and plate coupling means are installed on the upper and loweropenings of the trap units in such a way as to contract or extend. Thetrap and plate coupling means are extended at normal times toair-tightly seal gaps between the upper and lower plates and the trapunits, and are contracted when the trap units are rotated in apredetermined direction for the replacement of the trap units, thusallowing the trap units to smoothly rotate.

The servo motor is mounted to a lower surface of the lower plate while ashaft of the servo motor is connected to a lower end of the verticalshaft, and rotates forwards or backwards in response to a signal outputfrom a control unit, thus rotating the trap units within a predeterminedangular range.

The pressure gauges are mounted to the byproduct inlet port and thecasing, respectively, thus detecting and displaying pressure in a trapunit that is currently collecting the byproducts and pressure in thecasing, and simultaneously transmit detected pressure signals to thecontrol unit, thus allowing a time when the trap unit is replaced withanother one to be indicated.

The upper and lower isolation valves are mounted on the byproduct inletand outlet ports, respectively, so as to control the ingress of thebyproducts into a specific trap unit or the discharge of the byproductsfrom the trap unit.

The cleaning-water supply and discharge valves and the dry-gas supplyand exhaust valves are provided on the cleaning-water supply anddischarge ports and the dry-gas supply and exhaust ports, respectively,thus controlling the supply and discharge of cleaning water and dry gas.

The control unit is provided with a control program, timers for settingthe time supplying cleaning water and dry gas, and cleaning-number andpressure setting parts. The control unit controls the operation of theservo motor, the trap and plate coupling means, and various kinds ofvalves.

The control unit includes a pressure-difference comparison part tocompare pressure in the casing with pressure in the trap unit collectingthe byproducts, thus detecting a pressure difference, timers for settinga cleaning-water supplying time and a dry-gas supplying time, andsetting parts for setting a cleaning number and pressure.

Further, a thermoelement is mounted to an outer portion of each of thetrap units. When the trap unit is collecting the byproducts, thethermoelement is operated such that the trap unit maintains lowtemperature, thus increasing a collecting effect. Meanwhile, when thetrap unit filled with the byproducts is cleaned by the cleaning waterand is dried by the supply of the dry gas, the thermoelement conducts aheating operation at high temperature, thus increasing dryingefficiency.

Further, the dry-gas exhaust port connected to each of the trap units iscoupled to the byproduct discharge port connected to the vacuum pump. Asnecessary, the dry-gas supply and exhaust ports having the dry-gassupply and exhaust valves are formed through the upper and lower platesof the casing, the dry-gas exhaust port being coupled to the byproductdischarge port connected to the vacuum pump.

Each trap and plate coupling means includes an encoder motor which ismounted around each of the upper and lower openings of each of the trapunits and includes a ring-shaped rotor having on an inner surfacethereof a thread engaging with a thread of a bellows housing, a bellowshousing which has on an outer surface thereof the thread engaging withthe thread of the rotor of the encoder motor and is installed in therotor of the encoder motor to contract or extend a bellows in responseto a driving direction of the encoder motor, so that the bellows housingis in contact with or is spaced apart from each of the upper and lowerplates, and a bellows which is installed such that an outer end thereofis welded to an upper or lower end in the bellows housing and an innerend thereof is welded to an inner surface of the upper or lower openingof each of the trap units. The bellows contracts or extends in responseto a vertical moving direction and a moving distance of the bellowshousing coupled to the rotor of the encoder motor, thus maintainingairtightness between the bellows housing and each of the trap units. Thetrap and plate coupling means also includes a spring which iselastically installed between an end of the bellows housing fastened tothe rotor through a screw-type fastening method and an upper or lowersurface of each of the trap units, and an O-ring which is mounted toeach of upper and lower surfaces on an outer portion of the bellowshousing, thus sealing a contact part between the bellows housing andeach of the upper and lower plates.

Further, in order to accomplish the object, the present inventionprovides a method of controlling an automatically replaceable byproductcollecting apparatus in semiconductor producing equipment, includingclosing an upper isolation valve mounted to a byproduct inlet port, andopening a lower isolation valve mounted to a byproduct discharge port,when a replacement-time indicating signal, corresponding to pressurevariation in a trap unit that is currently operating, is input from aprocess chamber to a control unit, and thereafter, opening a dry-gasexhaust valve of a trap unit that has been cleaned and remains in awaiting mode, and opening a dry-gas exhaust valve provided between acasing and the byproduct discharge port; closing the lower isolationvalve and the dry-gas exhaust valve coupled to the trap unit that hasbeen cleaned and remains in the waiting mode, and contracting trap andplate coupling means, so that an upper or lower portion of each of thetrap units moves away from an upper or lower plate, when inlet pressureand outlet pressure of the trap unit that is currently operating arecompared with each other and it is determined that a pressure differenceis less than a preset value; driving a servo motor in a predetermineddirection to change positions of the trap units, and extending the trapand plate coupling means, thus maintaining the upper or lower portion ofeach of the trap units in close contact with the upper or lower plate,therefore maintaining airtightness; opening each of the upper and lowerisolation valves, supplying a predetermined amount of cleaning waterinto the trap unit that is filled with byproducts, maintaining the statefor a preset time, and thereafter opening a cleaning-water dischargevalve, thus discharging the cleaning water, and repeating thecleaning-water discharging operation a preset number of times; driving athermoelement mounted to an outer portion of each of the trap units fora preset time, thus heating the trap unit, and simultaneously openingthe dry-gas supply valve and the cleaning-water discharge valve; andstopping heating after a preset time has passed, and closing the dry-gassupply valve and the cleaning-water discharge valve, thus completing acleaning operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating a byproduct collecting apparatus insemiconductor fabricating equipment;

FIG. 2 is a view showing the appearance of an apparatus, according tothe present invention;

FIG. 3 is a plan sectional view showing the apparatus, according to thepresent invention;

FIG. 4 is a schematic block diagram of the apparatus, according to thepresent invention;

FIGS. 5 and 6 are perspective views showing the apparatus, according tothe present invention, when an outer casing and an upper lid have beenremoved;

FIG. 7 is an exploded perspective view showing a trap unit of theapparatus, according to the present invention;

FIGS. 8 and 9 are a bottom perspective view and a plan perspective viewshowing the state where the trap units, a vertical shaft, and a servomotor of the apparatus according to the present invention are coupled toeach other;

FIGS. 10 and 11 are an enlarged cutaway perspective view and an enlargedexploded perspective view showing a trap and plate coupling means of theapparatus, according to the present invention;

FIGS. 12 a and 12 b are sectional views showing the trap and platecoupling means of the apparatus, according to the present invention; and

FIG. 13 is a flowchart illustrating the method of the present invention.

MODE FOR THE INVENTION

Hereinafter, the preferred embodiment of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 2 is a view showing the appearance of an apparatus, according tothe present invention, FIG. 3 is a plan sectional view showing theapparatus, according to the present invention, FIG. 4 is a schematicblock diagram of the apparatus, according to the present invention,FIGS. 5 and 6 are perspective views showing the apparatus, according tothe present invention, when an outer casing and an upper lid have beenremoved, and FIG. 7 is an exploded perspective view showing a trap unitof the apparatus, according to the present invention.

FIGS. 8 and 9 are a bottom perspective view and a plan perspective viewshowing the state where the trap units, a vertical shaft, and a servomotor of the apparatus according to the present invention are coupled toeach other, FIGS. 10 and 11 are an enlarged cutaway perspective view andan enlarged exploded perspective view showing a trap and plate couplingmeans of the apparatus, according to the present invention, and FIGS. 12a and 12 b are sectional views showing the trap and plate coupling meansof the apparatus, according to the present invention, and FIG. 13 is aflowchart illustrating the method of the present invention.

Referring to the drawings, the apparatus of the present inventionincludes a cylindrical casing 4 which is open at upper and lower endsthereof. Traps are installed in the casing 4 to collect various kinds ofbyproducts. An upper lid 41 having a byproduct inlet port 43 and a lowerlid 42 having a byproduct outlet port 44 are provided on upper and loweropenings, respectively, to close the upper and lower openings. Theapparatus is installed between a process chamber 1 and a vacuum pump 2,and collects the byproducts produced from a semiconductor productionline.

The apparatus includes several trap units 5, upper and lower plates 6and 7, trap and plate coupling means 8, a servo motor 9, pressure gauges12 and 13, upper and lower isolation valves 14 and 15, cleaning-watersupply and discharge valves 16 and 17, dry-gas supply and exhaust valves18 and 19, and a control unit 10.

The trap units 5 are installed in the casing 4 at regular angularintervals via support ribs 1′ of a vertical shaft 11, which is providedin the center of the casing 4. In such a state, the trap units 5 areprovided between upper and lower plates 6 and 7 and are rotated forwardsor backwards according to the driving direction of the servo motor 9.While the trap units 5 are connected to the byproduct inlet and outletports 43 and 44, cleaning-water supply and discharge ports 45 and 46,and dry-gas supply and exhaust ports 47 and 48, one of the trap unitscollects byproducts, and the rest of the trap units are repeatedlycleaned.

The vertical shaft 11 supporting the trap units 5 passes through thecenter of each of the upper and lower plates 6 and 7. The upper andlower plates 6 and 7 are provided around the trap units 5, are connectedto the upper and lower lids 41 and 42 to be spaced apart therefrom by apredetermined interval, and are provided with the byproduct inlet andoutlet ports 43 and 44, the cleaning-water supply and discharge ports 45and 46, and the dry-gas supply and exhaust ports 47 and 48. The upperand lower plates 6 and 7 are provided on the upper and lower portions ofthe casing 4 in such a way as to contact the upper and lower openings ofthe trap units 5, and to make the byproduct inlet and outlet ports 43and 44, the cleaning-water supply and discharge ports 45 and 46, thedry-gas supply and exhaust ports 47 and 48 be selectively coupled to theupper and lower openings of the respective trap units 5.

The trap and plate coupling means 8 are installed on the upper and loweropenings of the trap units 5 in such a way as to extend or contract. Atnormal times, the trap and plate coupling means 8 are extended, thussealing the air between the upper and lower plates 6 and 7 and the trapunits 5. Meanwhile, when the trap units 5 rotate in a predetermineddirection, the trap and plate coupling means contract, thus allowing thetrap units 5 to smoothly rotate without contacting the upper and lowerplates 6 and 7.

The servo motor 9 is connected at a shaft thereof to the lower end ofthe vertical shaft 11. In such a state, the servo motor 9 is mounted tothe bottom of the lower plate 7. The servo motor 9 is rotated forwardsor backwards in response to the output signal of the control unit 10,thus rotating the trap units 5 within a predetermined angular range.

The pressure gauges 12 and 13 are respectively mounted on the byproductinlet port 43 and the casing 4, thus detecting and displaying thepressure in the trap unit 5 that is currently collecting the byproductand the pressure in the casing 4. Simultaneously, each of the pressuregauges 12 and 13 transmits the detected pressure signal to the controlunit 10, thus allowing a person to know the time when the trap unit 5will be replaced with another one.

The upper and lower isolation valves 14 and 15 are mounted to thebyproduct inlet and outlet ports 43 and 44, respectively, thuscontrolling the ingress of the byproducts into a specific trap unit 5 orthe discharge of the byproducts from the trap unit 5.

The cleaning-water supply and discharge valves 16 and 17 are mounted tothe cleaning-water supply and discharge ports 45 and 46 to control thesupply and discharge of cleaning water. The dry-gas supply and exhaustvalves 18 and 19 are mounted to the dry-gas supply and exhaust ports 47and 48 to control the supply and discharge of dry gas.

The control unit 10 controls the operation of the servo motor 9, thetrap and plate coupling means 8, and the valves, according to thecontrol program.

In this case, the control unit 10 is provided with a pressure-differencecomparison part 101 which detects the difference between the pressure inthe casing 4 and the pressure in the trap unit 5 which is collecting thebyproduct, timers 102 and 103 for setting cleaning-water and dry-airsupplying times, and cleaning number and pressure setting parts 104 and105.

Further, thermoelements 20 are additionally mounted on the outerportions of the trap units 5. When the byproducts are being collected,the thermoelements 20 allow the trap units 5 to maintain lowtemperature, thus increasing the collecting ability. Meanwhile, when thetrap unit 5 filled with the byproducts is cleaned using the cleaningwater and the interior of the trap unit 5 is dried using the dry gas,the thermoelements 20 heat the trap unit 5 to high temperature, thusincreasing drying efficiency.

The dry-gas exhaust port 48 connected to each trap unit 5 is coupled tothe byproduct outlet port 44 connected to the vacuum pump 2. Asnecessary, dry-gas supply and exhaust ports 47′ and 48′ having dry-gassupply and exhaust valves 18′ and 19′ are installed to pass through theupper and lower lids 41 and 42 of the casing 4. Each dry-gas exhaustport 48′ is coupled to the byproduct outlet port 44 connected to thevacuum pump 2.

Each trap and plate coupling means 8 includes an encoder motor 81, abellows housing 83, a bellows 84, a spring 85, and an O-ring 86. Theencoder motor 81 is provided with a ring-shaped rotor 82 having on aninner surface thereof a thread 821 that engages with a thread 831 of thebellows housing 83. The encoder motor 81 is mounted around each of theupper and lower openings of each trap unit 5.

The bellows housing 83 has on an outer surface thereof the thread 831that is fastened to the rotor 82 of the encoder motor 81 through ascrew-type fastening method. The bellows housing 83 is installed in therotor 82 of the encoder motor 81 and contracts or extends the bellows 84according to the driving direction of the encoder motor 81, and isbrought into contact with each of the upper and lower plates 6 and 7, oris spaced apart from each of the upper and lower plates 6 and 7.

The outer end of the bellows 84 is welded to the upper or lower end ofthe inner surface of the bellows housing 83, while the inner end of thebellows 84 is welded to the inner portion of each of the upper and loweropenings of each trap unit 5. According to the moving direction or themoving distance of the bellows housing 83 fastened to the rotor 82 ofthe encoder motor 81, the bellows 84 contracts or extends, thusair-tightly sealing the gap between the bellows housing 83 and each trapunit 5.

The spring 85 is elastically mounted between the end of the bellowshousing 83 fastened to the rotor 82 and the upper or lower surface ofeach trap unit 5.

The O-ring 86 is coupled to each of the upper and lower surfaces outsidethe bellows housing 83, and seals the junctions between the bellowshousing 83 and the upper and lower plates 6 and 7.

Meanwhile, the control method of the present invention includes the stepof opening the dry-gas exhaust valves 19. At the step, when a signalindicating a replacement time according to the variation in pressure ofthe trap unit 5 which is being operated is input from the processchamber 1 to the control unit 10, the upper isolation valve 14 mountedto the byproduct inlet port 43 is closed, and the lower isolation valve15 mounted to the byproduct outlet port 44 is opened. Thereafter, thedry-gas exhaust valves 19, connected to the trap units 5 that have beencleaned and remain in a waiting mode, are opened, and the dry-gasexhaust valve 19 connected between the casing 4 and the byproduct outletport 44 is opened.

Next, when the difference (pg1−pg2=pg) between the inlet pressure andthe outlet pressure of the trap unit 5 which is currently operating ismeasured and the measured difference is less than a preset value(|pg|<preset value), the dry-gas exhaust valves 19 connected to the trapunits which have been cleaned and remain in a waiting mode and the lowerisolation valve 15 are closed. The trap and plate coupling means 8 areoperated so as to contract, so that the upper and lower portions of eachtrap unit 5 are spaced apart from the upper and lower plates 6 and 7.

After the servo motor 9 is driven in a predetermined direction to changethe position of the trap units 5, the trap and plate coupling means 8 isoperated to extend, so that the upper and lower portions of each trapunit 5 come into close contact with the upper and lower plates 6 and 7,thus remaining airtight.

Next, each of the upper and lower isolation valves 14 and 15 is opened,and a predetermined amount of cleaning water is supplied to the trapunit 5, which was full of the byproducts. Such a state is maintained fora preset time (e.g., 2 to 5 minutes). Thereafter, the cleaning-waterdischarge valve 17 is opened, thus discharging cleaning water. Thisoperation is repeated a preset number of times (e.g. 4 to 6).

The thermoelements 20 mounted to the outer portion of each trap unit 5are driven for a preset time (e.g. 20 to 30 minutes), thus heating thetrap unit 5. Simultaneously, the dry-gas supply valves 18 and thecleaning-water discharge valves 17 are opened.

When the preset time has passed, the heating operation is ceased, andthe dry-gas supply valves 18 and the cleaning-water discharge valves 17are closed. Thereby, the cleaning operation is completed.

The operational effects of the present invention having theabove-mentioned construction and method will be described below.

First, the apparatus of the present invention includes the cylindricalcasing 4 sealed by the upper and lower lids 41 and 42. Several (2 or 3)trap units 5 each having the trap and plate coupling means 8, the upperand lower plates 6 and 7, and the servo motor 9, are installed in thecasing 4. The pressure gauges 12 and 13, the upper and lower isolationvalves 14 and 15, the cleaning-water supply and discharge valves 16 and17, the dry-gas supply and exhaust valves 18 and 19, and the controlunit 10 are mounted to the outer portion of the casing 4.

In this case, the trap units 5 are mounted via the support ribs 11′ tothe vertical shaft 11 which is rotatably provided in the center of thecasing 4 at a predetermined angular interval (e.g. if the trap units aretwo in number, the trap units are arranged at an angular interval of 180degrees, and if the trap units are three in number, the trap units arearranged at an angular interval of 120 degrees). In such a state,according to the driving direction of the servo motor 9, which engageswith the vertical shaft 11, the trap units are rotated forwards orbackwards by 180 degrees or 120 degrees between the upper and lowerplates 6 and 7. The trap units are coupled to the byproduct inlet andoutlet ports 43 and 44, the cleaning-water supply and discharge ports 45and 46, and the dry-gas supply and exhaust ports 47 and 48, which areinstalled to be connected to the upper and lower plates 6 and 7. One ofthe trap units 5 collects the byproducts. As such, while one of the trapunits 5 collects the byproducts, one or two trap units 5 are repeatedlycleaned using the cleaning water and the dry gas, such as nitrogen.

The internal construction of the trap units 5 is equal to theconstruction of the conventional byproduct collecting apparatus, exceptthat it has a smaller size.

Meanwhile, the casing 4 may have polygonal shapes, such as a symmetricalpolygonal shape or an asymmetrical polygonal shape, without beinglimited to the cylindrical shape.

Further, the upper and lower plates 6 and 7 are installed in the casing4 to be positioned under and above the upper and lower lids 41 and 42and spaced apart therefrom by a predetermined distance, while thevertical shaft 11 supporting the trap units 5 passes through the centersof the upper and lower plates 6 and 7. The upper and lower plates 6 and7 are located around the trap and plate coupling means 8 mounted to theupper and lower openings of the trap units 5 and are spaced apart fromthe upper and lower lids 41 and 42 by a predetermined interval. Theupper and lower plates are provided with the byproduct inlet and outletports 43 and 44, the cleaning-water supply and discharge ports 45 and46, and the dry-gas supply and exhaust ports 47 and 48.

Thus, when the trap units 5 are rotated clockwise or counterclockwise ata predetermined angle according to the driving direction of the servomotor 9, and the bellows 84 of each trap and plate coupling means 8 isextended by the operation of the trap and plate coupling means 8, theupper and lower openings of the trap units 5 are selectively connectedto the byproduct inlet and outlet ports 43 and 44, the cleaning-watersupply and discharge ports 45 and 46, and the dry-gas supply and exhaustports 47 and 48, which are mounted to the upper and lower plates 6 and7. Simultaneously, the trap units 5 are in close contact with the upperand lower plates 6 and 7 by the O-rings 86 mounted to the ends of thebellows 84 of the trap and plate coupling means 8, thus remainingairtight.

In this case, each trap and plate coupling means 8 is provided with theencoder motor 81 having the ring-shaped rotor 82, the bellows housing83, the bellows 84, the spring 85, and the O-ring 86. The trap and platecoupling means 8 are mounted to the upper and lower openings of the trapunits 5 in such a way as to contract or extend. At normal times, thetrap and plate coupling means 8 are extended, thus air-tightly sealingthe gaps between the upper and lower plates 6 and 7 and the trap units5. When the trap units 5 are rotated in a predetermined direction, thetrap and plate coupling means 8 contract, thus allowing the trap units 5to smoothly rotate without coming into contact with the upper and lowerplates 6 and 7.

The encoder motor 81 has the shape of a ring. The ring-shaped rotor 82having on the inner surface thereof the thread 821 which engages withthe thread 831 of the bellows housing 83 is rotatably installed in theencoder motor 81. The encoder motor 81 is secured around each of theupper and lower openings of each trap unit 5.

Further, the bellows housing 83 has on the outer circumference thereofthe thread 831 which engages with the thread 821 of the rotor 82 of theencoder motor 81 through a screw-type fastening method. The bellowshousing 83 is installed in the rotor 82 of the encoder motor 81 in sucha way as to move up and down, and moves up and down according to thedriving direction of the rotor 82 of the encoder motor 81, thuscontracting or extending the bellows 84. Further, the bellows housing 83makes each trap and plate coupling means 8 itself come into closecontact with the upper and lower plates 6 and 7 and be spaced apart fromthe upper and lower plates 6 and 7.

The bellows 84 has an extendable shape. The outer end of the bellows 84is welded to the upper or lower end of the inner portion of the bellowshousing 83, while the inner end of the bellows 84 is welded to the innerportion of the upper or lower opening of each trap unit 5. According tothe vertical moving direction and the moving distance of the bellowshousing 83 coupled to the rotor 82 of the encoder motor 81, the bellows84 is contracted or extended, thus air-tightly sealing the gap betweenthe bellows housing 83 and each trap unit 5.

Meanwhile, if the rotor 82 of the encoder motor 81 is fastened to thebellows housing 83 only through a screw-type fastening method, thebellows housing 83 may move up and down in the rotor 82 due to thetolerance of the threads when the bellows housing 83 moves up and downaccording to the rotating direction of the rotor 82. Further, when thebellows housing is extended, the upper or lower end of the bellowshousing 83 may not be in contact with the upper or lower plate 6 or 7.

Thus, according to the present invention, the spring 85 is installedbetween the inner end of the bellows housing 83 fastened to the rotor 82through the screw-type fastening method and the upper or lower surfaceof each trap unit 5. Due to such a construction, the bellows housing 83is biased to the upper or lower plate 6 and 7 by the elastic force ofthe spring 85. Thereby, when the bellows housing 83 moves up and downaccording to the rotating direction of the rotor 82, the bellows housing83 is not moved up and down in the rotor 82 because of the elastic forceof the spring 85 even though the threads have tolerance. Further, whenthe bellows housing 83 is extended, the upper or lower end of thebellows housing 83 is in close contact with the upper or lower plate 6or 7.

Moreover, according to the present invention, the O-ring 86 is installedin the groove formed in the upper or lower surface of the outer portionof the bellows housing 83. Thus, when the bellows housing 83 is moved upand down by the extension of the bellows 84, so the upper or lowersurface of the bellows housing 83 is in contact with the upper or lowerplate 6 or 7, the contact part of the bellows housing 83 and the upperor lower plate 6 and 7 is perfectly sealed by the O-ring 86. Thereby,the leakage of the byproducts through the gap can be prevented.

According to this embodiment, each trap and plate coupling means 8 usesthe encoder motor 81 having the ring-shaped rotor 82 as the drivingmeans. However, a hydraulic or pneumatic cylinder may be used as thedriving means, without being limited to the encoder motor. It isapparent to those skilled in the art that the same effect is achievedusing the hydraulic or pneumatic cylinder.

Further, according to this embodiment, each trap and plate couplingmeans 8 is installed on the upper or lower surface of each trap unit 5,thus adjusting the entire length of the trap unit, therefore connectingor disconnecting the trap unit 5 to or from the upper or lower plate 6or 7. Conversely, each trap and plate coupling means 8 may beconstructed such that the length of the byproduct inlet or outlet port43 or 44 is changed (i.e. the byproduct inlet or outlet port itself isconstructed to have the shape of a bellows), and may be installedbetween the upper or lower lid 41 or 42 and the upper or lower plate 6or 7 so that the upper or lower plate 6 or 7 moves up and down to theupper or lower opening of each trap unit 5. Those skilled in the art caneasily understand such a construction.

The servo motor 9 has a reduction gear therein. In the state where theservo motor 9 is mounted to the lower surface of the lower plate 7, theshaft of the servo motor 9 is coupled to the lower end of the verticalshaft 11 which is installed to pass through the centers of the upper andlower plates 6 and 7. The servo motor 9 rotates forwards or backwards inresponse to the output signal from the control unit 10, thus rotatingthe trap units 5 within a predetermined angular range, thereforechanging the position of the trap unit 5 which is full of the byproductsand the position of the trap units 5 which are cleaned and remain in awaiting mode.

Meanwhile, the pressure gauges 12 and 13 are installed to the byproductinlet port 43 which are connected to the trap units 5 through the upperlid 41 and the upper plate 6, and the casing 4, respectively. Thepressure gauges 12 and 13 detect and display the pressure in the trapunit 5 that is currently collecting the byproducts and the pressure inthe casing 4. Simultaneously, the pressure gauges 12 and 13 transmit thedetected pressure signals to the control unit 10, so that the controlunit 10 indicates the replacement time of the trap unit 5.

Since the upper and lower isolation valves 14 and 15 are mounted on thebyproduct inlet and outlet ports 43 and 44, respectively, the controlunit 10 can control the ingress and discharge of the byproducts whichare fed into and then discharged from a specific trap unit 5 among theseveral trap units 5 that is connected between the process chamber 1 andthe vacuum pump 2, according to the predetermined control program.

Further, the cleaning-water supply and discharge valves 16 and 17 andthe dry-gas supply and exhaust valves 18 and 19 are mounted to thecleaning-water supply and discharge ports 45 and 46 and the dry-gassupply and exhaust ports 47 and 48, respectively. Thus, the control unit10 controls the supply and discharge of the cleaning water and the drygas to and from the trap units 5 excluding the trap unit which iscurrently connected between the process chamber 1 and the vacuum pump 2,that is, the waiting trap units 5, for a predetermined time (e.g. 2 to 5minutes) by a predetermined amount and a predetermined number of times(e.g. 4 to 6). While one of the trap units 5 collects the byproducts,the rest of the trap units 5 are cleaned and remain in a waiting mode.When the trap unit 5 which is currently collecting the byproducts issaturated with the byproducts, the operation of replacing the trap unit5 with another trap unit is automatically conducted. That is, the trapunit saturated with the byproducts moves to another place, and one ofthe trap units which are cleaned and remain in the waiting mode moves tothe byproduct inlet and outlet ports 43 and 44. Thereby, the operationof collecting the byproducts in a clean trap unit can be continuouslyconducted.

Meanwhile, the control unit 10 is provided with the pressure-differencecomparison part 101, the timers 102 and 103 for setting thecleaning-water and dry-gas supplying times, and the cleaning-number andpressure setting parts 104 and 105. The internal pressure of the casing4 and the pressure of the trap unit 5 which is collecting the byproductsare input from the pressure gauges 12 and 13 to the pressure-differencecomparison part 101, so that the pressure-difference comparison part 101detects the pressure difference between the casing 4 and the trap unit5. Although not shown in the drawings, the control unit is provided witha drive part for driving the valves, the motor, and the thermoelements20, and is provided with a predetermined control program. By executingthe control program, the driving operation of the servo motor 9, thetrap and plate coupling means 8, the valves, and the thermoelements iscontrolled.

In this case, the times set by the timers 102 and 103 for setting thecleaning-water and dry-gas supplying times, and the cleaning number andpressure-difference set by the cleaning-number and pressure settingparts 104 and 105 may be changed according to the size of the collectingapparatus or the kind of byproducts produced in the semiconductormanufacturing process. When the waiting time is provided for 2 to 5minutes after the cleaning water is supplied, the cleaning operation isrepeated 4 to 6 times, and the supply of the dry gas and the heatingoperation through the thermoelements 20 are conducted for 8 to 10minutes, most of the byproducts collected in the trap unit 5 may beremoved by the cleaning water. Moreover, all the molecules of theremaining byproducts can be discharged.

Meanwhile, when the byproducts are collected through the trap unit 5connected to the byproduct supply port 43, the efficiency of collectingthe byproducts is low if only the temperature of various kinds ofbyproducts fed and collected in the trap unit 5 is used. Further, whenthe trap unit 5 is saturated with the byproducts, the trap unit isrotated to a predetermined direction and is then cleaned using cleaningwater or dry gas. However, the cleaning and drying operation may not besmoothly conducted at normal temperature.

Thus, according to the present invention, several thermoelements 20 areadditionally mounted to the outer portions of the trap units 5. Thereby,in order to keep an associated trap unit 5 at a low temperature when thebyproducts are collected, the thermoelements 20 are operated as coolingdevices, thus increasing the effect of collecting the byproducts.Meanwhile, when the trap unit 5 filled with the byproducts is cleaned bythe cleaning water and thereafter the interior of the trap unit 5 isdried through the dry gas, the thermoelements 20 are operated as heatingdevices, thus increasing a dry efficiency through heating.

In this case, each of the thermoelements 20 is a PTC device havingconstant-temperature characteristics. The cooling operation and theheating operation of the thermoelements 20 are changed by changing thesupply direction of DC voltage supplied to the thermoelements 20. Forexample, when one desires to operate the thermoelements 20 as a coolingdevice, positive voltage is supplied to a first terminal and negativevoltage is supplied to a second terminal. Conversely, when one desiresto operate the thermoelements 20 as a heating device, negative voltageis supplied to the first terminal and positive voltage is supplied tothe second terminal.

Further, according to the present invention, the cleaning-waterdischarge port 46 is coupled to a cleaning-water collecting container(not shown) which is installed outside the apparatus of the invention,thus causing the cleaning water to remain in the trap units for apredetermined period of time. Thereby, when the cleaning water in whichvarious kinds of byproducts are soluble is discharged, the cleaningwater is collected in the additional cleaning-water collectingcontainer, so that environmental pollution is prevented. Further, thedry-gas exhaust port 48 connected to each trap unit 5 is coupled to thebyproduct discharge port 44 connected to the vacuum pump 2, so that thedry gas passing through the trap unit 5 which is being cleaned can becollected in a gas collecting unit (not shown) through the vacuum pump 2without being discharged to the outside.

Meanwhile, as necessary, the dry-gas supply and exhaust ports 47′ and48′ having the dry-gas supply and exhaust valves 18′ and 19′ may beinstalled in the casing 4 through the upper and lower lids 41 and 42 ofthe casing 4, in addition to the dry-gas supply and exhaust ports 47 and48 connected to the trap units 5. In this case, the dry-gas exhaust port48′ is coupled to the byproduct discharge port 44 connected to thevacuum pump 2.

In order to replace the trap unit 5 that is filled with the byproductswith the new trap unit that has been cleaned, the trap and platecoupling means 8 are operated to separate the trap units 5 from theupper and lower plates 6 and 7. At this time, the casing 4 may be soiledby the byproducts discharged from the trap unit into the casing. Inorder to clean the soiled casing 4, the dry gas is supplied ordischarged through the dry-gas supply or exhaust port 47′ or 48′ suchthat the dry gas passes through the interior of the casing 4. Throughsuch a method, it is possible to completely clean the interior of thedirty casing 4.

Meanwhile, when various kinds of byproducts produced in thesemiconductor manufacturing process are collected using the apparatus ofthis invention, the control unit 10 continues to detect whether thesignal indicating the replacement time is input from the process chamber1 in response to the pressure variation in the pressure of the trap unit5 that is currently being operated.

That is, in the normal state, the byproducts produced in the processchamber are collected in one of the trap units 5 installed in thecollecting apparatus, that is, the trap unit 5 which is currentlyconnected to the byproduct inlet port 43. As the semiconductormanufacturing process is performed, the total amount of the byproductscollected in the associated trap unit 5 is gradually increased.Consequently, the entire passage extending from the process chamber 1 tothe vacuum pump 2 is blocked by the trap unit 5.

As such, the trap unit 5 must be automatically replaced with a new trapunit, before the trap unit 5 provided between the process chamber 1 andthe vacuum pump 2 is completely blocked. The process chamber 1determines that automatic replacement is required.

As the passage of the trap unit 5 is narrowed, it is difficult tomaintain a vacuum created by the vacuum pump 2 in the process chamber 1.Consequently, this causes a rise of pressure in the process chamber 1and hinders the control of pressure.

Further, the amount of the byproducts collected in the trap unit 5 whichis collecting the byproducts now can be estimated using the amount ortime of the production which is progressed in the process chamber 1.

Thus, the automatic replacement signal determined by the rise inpressure, the production amount, the production time, etc. istransmitted from the process chamber 1 to the control unit 10, so thatthe trap unit is automatically replaced with another one.

In this case, the pressure means the pressure applied to a waferprocessing operation in the process chamber 1. The pressure is variedaccording to the applied process. If the trap unit 5 is blocked, so thatit cannot maintain pressure lower than the process pressure, it isdifficult to control the process pressure. Thus, this is recognized asthe time when the trap unit 5 is to be replaced with another one.

In this case, the process chamber 1 determines the replacement time andannounces the replacement time for the trap unit 5. The degree of risein pressure providing the replacement signal depends on the appliedprocess of the process chamber.

For example, when the process pressure of the process chamber which ismass producing now is set to 2 Torr and the pressure exceeds 2 Torr, sothat it is difficult to control the pressure, the process chambergenerates an alarm signal. At this time, it is necessary to replace thetrap unit with another one.

The pressure difference between the trap unit 5 and the casing 4 is setto about 0.1 Torr (100 mTorr) or less by the pressure setting part 105so as to prevent a problem caused by the pressure difference even thoughthe trap unit 5 contracts.

As such, when the automatic replacement signal is input from the processchamber 1, the control unit 10 closes the upper isolation valve 14, thusisolating the trap unit 5 from the process chamber 1.

At this time, the lower isolation valve 15 is opened, so that thepumping operation is continuously performed in the trap unit 5 of theprocess area.

Further, in order to create a vacuum in two trap units 5 of the cleaningarea, the dry-gas exhaust valves 19 connected to the respective trapunits 5 are opened. Simultaneously, in order to create a vacuum in thecasing 4, the dry-gas exhaust valve 19 connected to the byproductdischarge port 44 is opened. Consequently, a vacuum is created in thecasing 4 and the trap units 5.

Meanwhile, in order to automatically replace the trap unit 5, the upperand lower sealing parts of the trap unit 5 must be opened. Thus, thepressure in the trap units 5 must be identical with the pressure in therest of the space in the casing 4. This must be checked beforehand.

Thus, the control unit 10 reads the pressure in the trap unit 5 whichcollects the byproducts, through the pressure gauge 12. The externalspace of the trap units 5, that is, the pressure in the casing 3, isread through the pressure gauge 13. Thereafter, the difference(pg1−pg2=pg) between the inlet pressure and the outlet pressure of thetrap unit 5 which is currently being operated is measured.

As a result, when the pressure difference is larger than the presetvalue (e.g. 100 mTorr), namely, /pg/≧the preset value, the valves remainopen, so as to pump the trap units 5 and other spaces (e.g. the interiorof the casing 4), as described above. When the pressure differencebetween the pressure gauges 12 and 13 is lower than the preset value,namely, /pg/<the preset value, the lower isolation valve 15 and thedry-gas exhaust valves 19 connected to the trap units 5, which arecleaned and remain in the waiting mode, are closed.

Subsequently, the trap and plate coupling means 8 are contracted so asto reduce the overall length of the trap units 5. Thereby, the upper andlower portions of each trap unit 5 are spaced apart from the upper andlower plates 6 and 7. Afterwards, the upper and lower isolation valves14 and 15 are closed to separate the cleaning line from the byproductcollecting line.

As described above, the trap and plate coupling means 8 are constructedso that the bellows 84 are installed to the upper and lower portions ofthe trap units 5 to be contracted or extended, and the O-rings 86 aremounted to the uppermost and lowermost parts of the bellows housings 83to bring the bellows housings 83 into airtight contact with the upperand lower plates 6 and 7. The bellows housing 83, contracting eachbellows 84 as shown in FIG. 12 a or extending each bellows 84 as shownin FIG. 12 b, has on the outer circumferential surface thereof thethread 831. The thread 821 is formed on the inner surface of the rotor82 of each of the upper and lower encoder motors 81 to correspond to thethread 831.

Further, the encoder motor 81 is coupled to the outer portion of therotor 82 such that the encoder motor is not separated from the rotor 82.The spring 85 is installed between the rotor 82 and the bellows housing83 so that the upper or lower portion of each trap unit 5 is in closecontact with the upper or lower plate 6 or 7.

Thus, the rotor 82 of the encoder motor 81 moves the bellows housing 83up and down, so that the bellows 84 is contracted or extended, andthereby the upper or lower portion of each trap unit 5 is spaced apartfrom or is in close contact with the upper or lower plate 6 or 7. Atthis time, the spring 85 enhances the contact force.

Meanwhile, the control unit 10, which contracts the several trap units 5using the trap and plate coupling means 8, drives the servo motor 9 in apredetermined direction, thus changing the position of the trap units 5.

Since the shaft of the servo motor 9 rotating the trap units 5 isconnected to the vertical shaft 11 rotating the trap units 5 via thesupport ribs 11′, the trap units 5 are rotated along with the verticalshaft 11 according to the rotating direction of the servo motor 9, andare changed in position. The servo motor 9 can rotate the three trapunits 5 clockwise or counterclockwise by an angle of 120 degrees.

Of course, the angle may be changed depending on the number of the trapunits 5. If the number of trap units 5 is two, the angle may be 180degrees. Further, if the number of trap units 5 is four, the angle maybe 90 degrees.

As such, when the position of the trap units 5 is changed, the controlunit 10 moves the trap and plate coupling means 8 in the oppositedirection, that is, moves the trap and plate coupling means 8 such thatthey are extended. Thereby, the upper or lower portion of each of thetrap units 5 comes into close contact with the upper or lower plate 6 or7 to remain airtight.

Subsequently, in order to clean the trap unit 5 collecting thebyproducts, the upper and lower isolation valves 14 and 15 and thecleaning-water supply valve 16 are opened, so that a predeterminedamount of cleaning water is supplied to the trap unit 5 which is full ofthe byproducts. This state is maintained for a preset time (2 to 5minutes) such that the byproducts are soluble in the cleaning water.Thereafter, the cleaning-water discharge valve 17 is opened to dischargethe cleaning water. The operations are repeated a preset number of times(i.e. a number which is set to sufficiently dissolve the byproducts;e.g. 4 to 6).

When the cleaning operation has been completed, the thermoelements 20mounted to the outer portion of each of the trap unit 5 are driven for apreset time (e.g. 20 to 30 minutes), thus heating the trap unit 5.Simultaneously, the dry-gas supply valve 18 and the cleaning-waterdischarge valve 17 are opened, thus discharging the dry gas and thecleaning water.

As such, when the trap unit 5 has been cleaned and dried by heating andsupplying the dry gas for a preset time (i.e. 20 to 30 minutes), thepower supplied to the thermoelements 20 is cut off, so that the heatingoperation is ceased. The dry-gas supply valve 18 and the cleaning-waterdischarge valve 17 are closed, and the cleaning operation is completed.The trap unit remains in the waiting mode for the subsequent collection.

When the collection amount of the automatically replaced trap unit 5 isincreased, and an automatic replacement signal is input from the processchamber 1, the automatic replacing operation and the cleaning operationare repeatedly conducted in the above-mentioned order. In this case, therotating direction of the servo motor 9 rotating the trap units 5 andthe area to be cleaned may be changed.

For example, the servo motor 9 recognizes the encoder position in therange from zero to 360 degrees, when turned once clockwise. If thecurrent encoder position is zero, the servo motor 9 rotates clockwise by120 degrees, and the trap unit of the first cleaning area is cleanedwhen the trap unit is automatically replaced in the collecting apparatushaving three trap units.

Further, when the current encoder position is 120 degrees, the servomotor 9 rotates counterclockwise by 240 degrees, so that the trap unitof the first cleaning area is cleaned.

When the current encoder position is 240 degrees, the servo motor 9rotates clockwise by 120 degrees, and the trap unit of the firstcleaning area is cleaned.

When the rotating method of the servo motor 9 is set in this way, thecleaning operation is conducted in the first cleaning area. Meanwhile,when the rotating method is set to be opposite to the above-mentionedmethod, the cleaning operation is conducted in the second cleaning area.

Although the preferred embodiment of the present invention has beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

INDUSTRIAL APPLICABILITY

As described above, the present invention provides an automaticallyreplaceable apparatus for collecting byproducts in semiconductorproducing equipment and a method of controlling the apparatus, in whichseveral trap units are rotatably installed in the collecting apparatusto collect byproducts produced during the semiconductor fabricatingprocess, such as ignitable gas, corrosive gas, noxious gas or harmfulcompounds, such that, when a predetermined amount of byproduct iscollected in any one of the trap units, the task of collection of thebyproduct is automatically transferred to another trap unit which hasbeen cleaned, thus increasing the operation rate of the byproductcollecting apparatus, therefore increasing the production ofsemiconductors, preventing injuries to workers due to the effluence ofharmful substances or noxious gases which may be produced when thebyproduct collecting apparatus is replaced with another one, andensuring safety.

1. An automatically replaceable collecting apparatus for collectingbyproducts produced in a semiconductor production line, the collectingapparatus being constructed so that a trap collecting various kinds ofbyproducts is installed in a casing which is open at a top and bottomthereof and so that a lid having each of a byproduct inlet port and abyproduct outlet port is mounted to each of upper and lower openings ofthe casing to close each of the upper and lower openings, and beinginstalled between a process chamber and a vacuum pump, the collectingapparatus comprising: a plurality of trap units mounted to a verticalshaft at regular angular intervals, and rotating leftwards or rightwardsbetween upper and lower plates in response to a driving direction of aservo motor, one of the trap units collecting the byproducts and therest of the trap units being repeatedly cleaned; the upper and lowerplates supporting the vertical shaft to which the trap units are mountedsuch that the vertical shaft passes through centers of the upper andlower plates, and being installed to be spaced apart from the upper andlower lids by a predetermined interval, so that the upper and lowerplates contact the upper and lower openings of the trap units at upperand lower positions of the casing, the upper and lower plates connectingbyproduct inlet and outlet ports, cleaning-water supply and dischargeports, and dry-gas supply and exhaust ports to the respective trapunits; trap and plate coupling means extended at normal times toair-tightly seal gaps between the upper and lower plates and the trapunits, the trap and plate coupling means being contracted when the trapunits are rotated in a predetermined direction for the replacement ofthe trap units, thus allowing the trap units to smoothly rotate; theservo motor mounted to a lower surface of the lower plate while a shaftof the servo motor is connected to a lower end of the vertical shaft,and rotating forwards or backwards in response to a signal output from acontrol unit, thus rotating the trap units within a predeterminedangular range; and the control unit for controlling the operation of theservo motor, the trap and plate coupling means, and various kinds ofvalves according to a control program.
 2. The automatically replaceablecollecting apparatus according to claim 1, wherein two, three, or fourtrap units are installed in the casing at angles of 180 degrees, 120degrees, or 90 degrees.
 3. The automatically replaceable collectingapparatus according to claim 1, further comprising: a pressure gaugemounted to each of the byproduct inlet port and the casing, thusdetecting and displaying pressure in a trap unit that is currentlycollecting the byproducts and pressure in the casing, and simultaneouslytransmitting detected pressure signals to the control unit, thusallowing a time when the trap unit is replaced with another one to beindicated.
 4. The automatically replaceable collecting apparatusaccording to claim 3, further comprising: upper and lower isolationvalves mounted on the byproduct inlet and outlet ports, respectively, soas to control the ingress of the byproducts into a specific trap unit orthe discharge of the byproducts from the trap unit.
 5. The automaticallyreplaceable collecting apparatus according to claim 1, furthercomprising: cleaning-water supply and discharge valves and dry-gassupply and exhaust valves provided on the cleaning-water supply anddischarge ports and the dry-gas supply and exhaust ports, respectively,thus controlling the supply and discharge of cleaning water and dry gas.6. The automatically replaceable collecting apparatus according to anyone of claims 1 to 5, wherein the control unit comprises: apressure-difference comparison part to compare pressure in the casingwith pressure in the trap unit collecting the byproducts, thus detectinga pressure difference; timers for setting a cleaning-water supplyingtime and a dry-gas supplying time; and setting parts for setting acleaning number and pressure.
 7. The automatically replaceablecollecting apparatus according to claim 1, further comprising: athermoelement mounted to an outer portion of each of the trap units, thethermoelement performing a cooling function when the trap unit collectsthe byproducts, and generating heat when the trap unit is dried afterbeing cleaned.
 8. The automatically replaceable collecting apparatusaccording to claim 1, wherein the dry-gas exhaust port connected to eachof the trap units is coupled to the byproduct discharge port connectedto the vacuum pump.
 9. The automatically replaceable collectingapparatus according to claim 1, wherein the dry-gas supply and exhaustports having the dry-gas supply and exhaust valves are formed throughthe upper and lower plates of the casing, the dry-gas exhaust port beingcoupled to the byproduct discharge port connected to the vacuum pump.10. The automatically replaceable collecting apparatus according toclaim 1, wherein the trap and plate coupling means is installed betweeneach of the upper and lower lids and each of the upper and lower plates,or is installed around each of the upper and lower openings of each ofthe trap units.
 11. The automatically replaceable collecting apparatusaccording to claim 10, wherein the trap and plate coupling means,installed around each of the upper and lower openings of each of thetrap units, comprises: an encoder motor mounted around each of the upperand lower openings of each of the trap units, and comprising aring-shaped rotor which has on an inner surface thereof a threadengaging with a thread of a bellows housing; the bellows housing havingon an outer surface thereof the thread engaging with the thread of therotor of the encoder motor, and installed in the rotor of the encodermotor to contract or extend a bellows in response to a driving directionof the encoder motor, so that the bellows housing is in contact with oris spaced apart from each of the upper and lower plates; and the bellowsinstalled such that an outer end thereof is welded to an upper or lowerend in the bellows housing and an inner end thereof is welded to aninner surface of the upper or lower opening of each of the trap units,the bellows contracting or extending in response to a vertical movingdirection and a moving distance of the bellows housing coupled to therotor of the encoder motor, thus maintaining airtightness between thebellows housing and each of the trap units.
 12. The automaticallyreplaceable collecting apparatus according to claim 11, furthercomprising: a spring installed between an end of the bellows housingfastened to the rotor through a screw-type fastening method and an upperor lower surface of each of the trap units, thus biasing the bellowshousing to the upper or lower plate.
 13. The automatically replaceablecollecting apparatus according to claim 12, further comprising: anO-ring mounted to each of upper and lower surfaces on an outer portionof the bellows housing, thus sealing a contact part between the bellowshousing and each of the upper and lower plates.
 14. A method ofcontrolling an automatically replaceable byproduct collecting apparatusin semiconductor producing equipment, comprising: closing an upperisolation valve mounted to a byproduct inlet port, and opening a lowerisolation valve mounted to a byproduct discharge port, when areplacement-time indicating signal, corresponding to pressure variationin a trap unit that is currently operating, is input from a processchamber to a control unit, and thereafter, opening a dry-gas exhaustvalve of a trap unit that has been cleaned and remains in a waitingmode, and opening a dry-gas exhaust valve provided between a casing andthe byproduct discharge port; closing the lower isolation valve and thedry-gas exhaust valve coupled to the trap unit that has been cleaned andremains in the waiting mode, and contracting trap and plate couplingmeans, so that an upper or lower portion of each of the trap units movesaway from an upper or lower plate, when inlet pressure and outletpressure of the trap unit that is currently operating are compared witheach other and it is determined that a pressure difference is less thana preset value; driving a servo motor in a predetermined direction tochange positions of the trap units, and extending the trap and platecoupling means, thus maintaining the upper or lower portion of each ofthe trap units in close contact with the upper or lower plate, thereforemaintaining airtightness; opening each of the upper and lower isolationvalves, supplying a predetermined amount of cleaning water into the trapunit that is filled with byproducts, maintaining the state for a presettime, and thereafter opening a cleaning-water discharge valve, thusdischarging the cleaning water, and repeating the cleaning-waterdischarging operation a preset number of times; driving a thermoelementmounted to an outer portion of each of the trap units for a preset time,thus heating the trap unit, and simultaneously opening the dry-gassupply valve and the cleaning-water discharge valve; and stoppingheating after a preset time has passed, and closing the dry-gas supplyvalve and the cleaning-water discharge valve, thus completing a cleaningoperation.
 15. The method according to claim 14, wherein a waiting timeafter the supply of the cleaning water is 2 to 5 minutes, the number oftimes the cleaning water is supplied and discharged is 4 to 6, and atime period for supplying dry gas and heating using the thermoelement is20 to 30 minutes.